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Antennas and Propagation Magazine, IEEE

Issue 5 • Date Oct. 2012

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Displaying Results 1 - 25 of 89
  • [Front cover]

    Page(s): c1
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  • CST STUDIO SUITE 2012 [Advertisement]

    Page(s): c2
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  • Table of contents

    Page(s): 3
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  • Information for contributors

    Page(s): 4
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  • Magazine Staff

    Page(s): 5 - 6
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  • AP-S Officers and Administrative Committee

    Page(s): 7
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  • Feature articles and contributions solicited

    Page(s): 7
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  • President's Message

    Page(s): 8 - 9
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  • Call for papers

    Page(s): 10 - 12
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  • We look forward to welcoming you to the 2013 IEEE International Symposium on Antennas and Propagation and USNC-URSI National Radio Science Meeting [Steering Committee]

    Page(s): 13
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  • On Understanding the Radiation Mechanism of Reflectarray Antennas: An Insightful and Illustrative Approach

    Page(s): 14 - 38
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (15978 KB) |  | HTML iconHTML  

    This article presents a unique point of view for microstrip reflectarrays. Through the effective utilization of graphical visualization of the scattered fields from the reflectarrays, one can gain insightful understanding into the fundamental workings of these antennas. The most important part of the reflectarray analysis and design is the accurate characterization of the individual reflectarray element for reflection phase performance. Using this visualization approach, reflectarray elements are characterized in unit-cell environments. This exercise aids in identifying the important geometrical parameters of the element that contribute to the reflection phase shift. These elements are then placed in an actual reflectarray environment, and the performance of the reflectarray is evaluated through full-wave electromagnetic simulations and measurements. It is validated that this technique can be successfully used to analyze, design, and potentially diagnose reflectarray antennas. View full abstract»

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  • To all IEEE Life Members

    Page(s): 38
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  • Changes of Address or Delivery Problems

    Page(s): 38
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  • Getting the magazine by air freight

    Page(s): 38
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  • Correction [to "some electromagnetic equivalence theorems unified by a single theorem and generalized to the nonlinear case"]

    Page(s): 39
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1551 KB)  

    Figure 2 in the feature article by Ali Uzer, "Some Electromagnetic Equivalence Theorems Unified by a Single Theorem and Generalized to the Nonlinear Case" (ibid.ne, vol 54, no 3, June 2012, pp. 86-99) was omitted. It is reproduced here. The Magazine regrets the omission. View full abstract»

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  • Electromechanical Coupling Analysis of Ground Reflector Antennas Under Solar Radiation

    Page(s): 40 - 57
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (12731 KB)  

    The surface-accuracy design criterion for the next-generation reflector antennas for the deep-space instrumentation project in China was 0.1 mm rms. However, these antennas have no radome or air-conditioned ventilation to protect against solar radiation. Therefore, the effect on the antenna's electromagnetic performance of thermal deformation due to solar radiation must be carefully evaluated. For this engineering problem, a 40-m reflector antenna was selected as the research object. First, the heat fluxes from direct solar radiation, sky-scattering radiation, and ground-reflected radiation on the antenna's surface were calculated, based on the antenna's location, date, and time. Second, the temperature distribution of the whole antenna was obtained with the Finite-Element Method (FEM), considering three methods of heat transfer: conduction, convection, and radiation. A temperature experiment was then designed via a 7.3-m Cassegrain antenna. The results indicated the validity of the previous heat flux and temperature analyses. Engineering knowledge of the thermal impact on the antenna's radiation was essential to improve the overall design and construction of the antenna. Third, a thermal-structural analysis was carried out with ANSYS. Finally, the electromagnetic parameters of the antenna were calculated using a far-field pattern formula, and three main electromagnetic parameters - the gain loss, the sidelobe level, and the pointing error - were considered in detail. The results of the analysis showed that the degradation of the electromagnetic performance was not only dependent on the rms amount of structural deformation, but also on the distribution of the deformation, especially for the sidelobe level and pointing error. The analysis method and results can be referenced for the design of next-generation reflector antennas. View full abstract»

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  • Inflatable Antenna for Space-Borne Microwave Remote Sensing

    Page(s): 58 - 70
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3921 KB) |  | HTML iconHTML  

    Although inflatable antennas represent a new and untested technology for remote-sensing applications, the advantages of small volume, low cost, and low mass provide an incentive for people to invest in developing this technology. The space-borne inflatable antenna concept was evaluated for passive microwave sensing of ocean temperature, wind, and precipitation. A large-diameter (3 m), on-axis, parabolic-torus antenna, operating in the L/C- and X-band frequency ranges, was designed and measured. This paper describes the system design of the inflatable space-borne antenna, including the mechanical design, the dynamic analysis, the deployment demonstration, and other key technologies. A photogrammetry tool was used to detect the rms accuracy of the antenna reflector's surface. An NSI planar antenna near-field testing system was used to measure the antenna's patterns and gain. We also analyzed the possible errors resulting from the measurements. View full abstract»

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  • Correction [to "reflector antenna distortion compensation using sub-reflectarrays: simulations and experimental demonstration"]

    Page(s): 70
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (549 KB)  

    In the contribution to the June issue's AMTA Corner by Harish Rajagopalan, Shenheng Xu, and Yahya Rahmat- Samii, "Reflector Antenna Distortion Compensation Using Sub-Refl ectarrays: Simulations and Experimental Demonstration" (ibid., vol 54, no 3, June 2012, pp. 235-246), Figure 3a did not contain all of the intended information. The correct fi gure is reproduced here. View full abstract»

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  • Fast Electromagnetic Integral-Equation Solvers on Graphics Processing Units

    Page(s): 71 - 87
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4435 KB) |  | HTML iconHTML  

    A survey of electromagnetic integral-equation solvers, implemented on graphics processing units (GPUs), is presented. Several key points for efficient GPU implementations of integral-equation solvers are outlined. Three spatial-interpolation-based algorithms, including the Nonuniform-Grid Interpolation Method (NGIM), the box Adaptive-Integral Method (B-AIM), and the fast periodic interpolation method (FPIM), are described to show the basic principles for optimizing GPU-accelerated fast integral-equation algorithms. It is shown that proper implementations of these algorithms lead to very high computational performance, with GPU-CPU speed-ups in the range of 100-300. Critical points for these accomplishments are (i) a proper arrangement of the data structure, (ii) an “on-the-fly” approach, trading excessive memory usage with increased arithmetic operations and data uniformity, and (iii) efficient utilization of the types of GPU memory. The presented methods and their GPU implementations are geared towards creating efficient electromagnetic integral-equation solvers. They can also find a wide range of applications in a number of other areas of computational physics. View full abstract»

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  • Efficient Analysis of Electromagnetic Scattering from Electrically Large Complex Objects by Using Phase-Extracted Basis Functions

    Page(s): 88 - 108
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (7819 KB) |  | HTML iconHTML  

    Efficient analysis of electromagnetic-wave responses from electrically large complex objects is a crucial but difficult topic in many applications of electromagnetic engineering. Among various numerical methods, the Method of Moments (MoM) solves for surface- or volume-distributed equivalent currents, which are expanded in terms of basis functions. In this paper, the traveling-wave phase variation has been incorporated into the basis functions to enhance their capability of describing the equivalent surface currents induced over surfaces of perfect electric conductors (PECs). A rigorous derivation is first given as physical insight, to show that the induced surface current is composed of a traveling-wave term and several standing-wave terms. A phase-extracted basis function (PEBF) is then proposed to describe the traveling current wave, and is applied in solving the electromagnetic scattering from three-dimensional (3D) PEC objects with smooth surfaces. By hybridizing the phase-extracted basis function with higher-order hierarchical basis functions, a moving standing-wave (MSW) basis function is further introduced to describe both the traveling-wave and the standing-wave terms in the induced surface current. It is shown from several numerical examples that the moving standing-wave basis function has excellent performance for solving electromagnetic scattering from three-dimensional PEC objects with both smooth and non-smooth surfaces, as well as for three-dimensional PEC cavities. After that, the unique properties of the phase-extracted basis function are utilized in the “sparsification” of the MoM matrix, and in the fast calculation of wideband responses. With the aid of the phase-extracted basis function and the moving standing-wave basis functions, the total memory requirements and the computational time can be significantly reduced, while numerical solutions can be obtained with good accuracy. The advantages of the phase-extracted basis function- and the moving standing-wave basis functions in predicting electromagnetic scattering from electrically large complex objects are summarized before the conclusions are drawn. View full abstract»

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  • Joint Time-Frequency Analysis of Transient Electromagnetic Scattering from a Subsurface Target

    Page(s): 109 - 130
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    The complexity of transient electromagnetic scattering from objects in free space has been well known for years. Such complexity is mainly due to the high aspect dependency of the early-time response, and the interactions between the various scattering events. Attempts have been made to analytically and numerically study the transient scattering problem using time-frequency (TF) analysis. Using this technique, the occurrences of the scattering events and their frequency content can be revealed, which leads to further information about the actual scattering behavior. For the case of subsurface targets, the entire problem becomes more complicated with the introduction of a dielectric interface. Analytical solutions of such complicated electromagnetic problems are usually not available, and can only be numerically addressed in most cases. In this paper, a systematic study of transient scattering from some subsurface targets is presented. The various interactions between the target and the interface of the half-space can be clearly observed. The findings from this work have opened up some issues that are left for further investigation. View full abstract»

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  • Addendum [to "Fundamentals of Electromagnetic Units and Constants"]

    Page(s): 130
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    Since the article by K.T. Selvan, "Fundamentals of Electromagnetic Units and Constants" (IEEE Antennas and Propagation Magazine, Vol 54, no 3, June 2012, pp. 100-114) appeared in print, two relevant previous papers have come to the author's attention and are note here. Leo Young's article (2002) presents an interesting discussion, with examples, of conversion and comparison between different systems of electromagnetic units. The more recent article by Pelosi and Sellari (2010) provides a historical account of the measurement and naming of the velocity of light, c. View full abstract»

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  • z-Transform Frameworks for FDTD

    Page(s): 131 - 144
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2914 KB) |  | HTML iconHTML  

    This paper presents an integrated approach to taking a frequency-domain simulation problem into the discrete time domain, based on z transforms. The ideas are illustrated with free space, the Drude pole, and perfectly matched layer (PML) conversion examples, for both leapfrog time stepping and simultaneous time stepping. Numerical results for various perfectly matched layer methods are given. We then present a two-dimensional scattering example in which the conversion from frequency to discrete time is carried out. Numerical results are presented and compared with results from a Method-of-Moments formulation. View full abstract»

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  • High Temperature Dielectric Constant and Loss Tangent Measurements [advertisement]

    Page(s): 145
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  • Chapter News

    Page(s): 146 - 148
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The IEEE Antennas and Propagation Magazine covers all areas relating to antenna theory, design, and practice.

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W. Ross Stone